The invention relates generally to orthotic devices applied to or attached to the external surface or part of the human body in order to improve function.
More specifically, the invention embraces an orthotic device of minimum parts and capable of replacing the basic function of the human shoulder joint by efficiently providing simultaneously stability as well as mobility of the arm. Such replacement is needed when illness or injury renders the shoulder joint nonfunctional. The device is worn in an inconspicuous manner both during mobility and rest thereby making it universally applicable for the purpose of increasing the function of the human upper limb when it is limited by illness or injury.
Prior orthotic devices for providing stability of the human arm at the shoulder joint include those known as hemiplegic shoulder slings and as airplane splints. The shoulder sling provides only questionable support to the arm and forearm, is known to limit the use of the hand and is considered to have no appreciable effect on ultimate range of motion, or on pain and subluxation of the shoulder occurring despite its use. The airplane splint immobilizes the arm in a constant position, can be used for only short periods of time because of considerable pressure on the pelvic bone, and is a limiting factor in mobility.
Prior orthotic devices for providing mobility of the human arm at the shoulder joint include those primarily known as mobile arm supports and functional arm braces. The mobile arm supports (also known as ball-bearing forearm orthoses) are attached to a wheelchair and are thus suitable for the non-ambulatory patient only. The functional arm braces allow only certain motions at the flail shoulder but fail to provide sufficient stability and mobility when spasticity is a factor.
Prior art patents such as U.S. Pat. No. 1,340,630 issued to R. D. Maddox on May 18, 1920 and U.S. Pat. No. 2,859,746 issued to W. V. Roberson on Nov. 11, 1958 fail both in structure and purpose to attain the ends of the instant invention. Maddox shows a complexity of joints and connections of metallic rods with body, arm and forearm pads all adapted to retain the arm of the patient in any desired position relatively to the body during treatment for fracture and other injuries especially of the arm and shoulder. Roberson utilizes a ball-shaped pad and means for holding the pad in the armpit under pressure to support the shoulder joint of a dislocated shoulder and to enable the person to move his or her arm.
In summary, the various presently applicable orthotic devices do not satisfy as does the invention herein the need for a universal orthotic device capable of providing simultaneously stability and mobility at the shoulder joint, applicable both during ambulation and in a stationary position, and having the structural characteristics of an artificial ball and socket joint anchored to a body plate and operable by a lockable joint-actuating rod carrying an elbow support or trough connected to the rod.
The basic function of the human shoulder joint is to locate the arm in such a position that the use of the forearm, wrist and hand becomes functional during activities of daily living. This complex coordinated function is provided by simultaneous patterned movements of two muscle groups: extrinsic and intrinsic. The function of these muscles is a continuously coordinated task in which the intrinsic muscles anchor the humoral head in the glenoid fossa, thus providing stability for the arm, while the extrinsic muscles provide the dynamic forces needed to move the arm against gravity or resistance. The human shoulder joint is incongruous by nature, which means that the concave and convex surfaces are symmetrical. The concave surface is elongated and the convex surface is more circular thereby making the distance between them variable at each point during movement. For the human shoulder to provide stability and mobility, the simultaneous interaction of both intrinsic and extrinsic muscle groups is essential for function.
There are a number of clinical entities wherein the complex coordination of intrinsic and extrinsic muscle groups are absent or deficient. These occur as the result of illness or injury to the central nervous system, to the peripheral nervous system, as well as to the muscles and bony structures controlling and comprising the shoulder joint.
Lesions of the central nervous system such as the brain and the spinal cord cause imbalance between previously coordinated patterned movements with sequential facilitation or inhibition of certain intrinsic or extrinsic muscles of the shoulder joint. This imbalance renders certain muscles paretic or poorly responsive to volitional attempt at contraction, while other muscles become spastic, or showing excessive, uncontrollable and prolonged contraction. As the result of coexisting spasticity and paresis (e.g. in hemiplegia), an attempt at voluntary movement at the shoulder usually produces a stereotyped, abnormal and nonfunctional response. This pathological response at the shoulder limits or prevents any functional use of the forearm and hand which could otherwise be at times utilized meaningfully.
Lesions of the peripheral nervous system, such as the brachial plexus or its branches, may render certain muscles of the shoulder paretic, thus preventing stability and mobility of the shoulder joint. Such involvement prevents the functional use of the forearm and hand, the muscles of which may remain sufficiently innervated.
Diseases affecting shoulder girdle muscles, such as muscular dystrophy, also deprive the shoulder from stability and mobility with the resulting loss of function of the forearm and hand which may often be preserved.
Disease or injuries to the bony capsular and/or tendinous elements of the shoulder joint usually result in pain that limits its mobility and stability with consequent decrease or loss of function of the forearm and hand, such as the shoulder hand syndrome, or with involvement of the sympathetic nervous system such as the reflex sympathetic dystrophy syndrome.